Americium(III) oxide

Americium(III) oxide or americium sesquioxide is an oxide of the element americium. It has the empirical formula Am₂O₃. Since all isotopes of americium are only artificially produced, americium (III) oxide has no natural occurrence. The colour depends on the crystal structure, of which there are more than one. It is soluble in acids.^[2]

Americium(III) oxide

Names
Other names Americium sesquioxide
Identifiers
CAS Number	12254-64-7
3D model (JSmol)	Interactive image
InChI InChI=1S/2Am.3O/q2*+3;3*-2 Key: HPWBMQLLXMZFDK-UHFFFAOYSA-N
SMILES [O-2].[O-2].[O-2].[Am+3].[Am+3]
Properties
Chemical formula	Am2O3
Molar mass	534 g·mol−1
Density	11.77
Melting point	2,205 °C (4,001 °F; 2,478 K)
Structure
Crystal structure	Trigonal, hP5
Space group	P3m1, No. 164
Lattice constant	a = 381.7 pm, c = 597.1 pm[1]
Related compounds
Other cations	Curium(III) oxide
Related compounds	Americium dioxide Americium(II) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Formation

Americium(III) oxide can be made by heating americium dioxide in hydrogen at 600°C.^[3]

2 AmO₂ + H₂ → Am₂O₃ + H₂O

Forms

The hexagonal form is coloured tan, and the cubic form is coloured red-brown the same as persimmon.^[3] The cubic form converts to the hexagonal form on heating to 800°C.^[3] The cubic form is non-stoichimetric with variable oxygen composition. It darkens with increasing oxygen.^[3]